A refrigeration system for car air-conditioners has a refrigeration cycle. In this cycle, a gaseous refrigerant of high temperature and high pressure sent out of a compressor is condensed by a condenser and then made into mist-like refrigerant including a gaseous phase and a liquid phase by decompressing means such as an expansion valve. Then, the mist-like refrigerant evaporates while passing through an evaporator. Thereafter, the evaporated refrigerant returns to the compressor.
As a conventional evaporator used in the aforementioned refrigeration system, a laminated type evaporator is mainly used. The laminated type evaporator includes a plurality of tubular elements laminated in laminating direction and fins each interposed between the adjacent tubular elements, wherein each tubular element is formed by coupling a pair of plate-shaped formed plates in a face-to-face manner.
This kind of laminated type evaporator is large in cooling capacity and is low in air-side pressure loss, and therefore has excellent characteristics. In recent years, in view of an odor problem of an inside of a car or the like, an odor removal filter is sometimes installed in front of the evaporator. In this case, in order to secure the mounting space for such a filter, the evaporator tends to be required to reduce the thickness.
In meeting such a demand of reducing the thickness of the aforementioned laminated type evaporator, the following drawbacks have became clear.
First, since each tubular element having heat exchanging passages is formed by coupling a pair of plate-shaped formed plates formed by drawing processing using a press in a face-to-face manner, the portions where the pair of formed plates directly contact, i.e., the portions other than the heat exchanging passages, likely increase. Consequently, the cross-sectional area of the refrigerant passages decrease, which may cause high refrigerant side pressure drop and deteriorate the performance. As this countermeasure, it is considered to increase the height of the refrigerant passage by increasing the drawing amount of the formed plate to thereby enlarge the cross-sectional area of the passage. However, according this proposal, the tubular element becomes thick, and therefore the air-side passage between the adjacent tubular elements becomes smaller, resulting in a reduced size of the fin disposed in the air-side passage. Consequently, there is a possibility that the air-side pressure drop increases and that the heat transferring area of the fin decreases, which in turn causes a deterioration of the performance.
Second, in the aforementioned laminated type evaporator, the fin does not comes into contact with a portion where the pair of formed plates directly contact each other, and therefore surface efficiency deteriorates. Accordingly, the more the thickness of the tubular element becomes, the more the rate of non-contact portion of the fin increases. This may cause a deterioration of the cooling performance.
Third, in the aforementioned laminated type evaporator, since the tank portion and the tube portion (heat exchanging medium passage portion) are integrally formed in the plate-shaped formed plate, the tank portion where higher pressure resistance is required is also formed by a drawing processing. Accordingly, the thickness of the tank portion tends to become thinner than that of the tube portion (heat exchange medium passage portion). Accordingly, It is necessary to design the wall thickness on the basis of the tank portion. As a result, even if the tube portion has enough pressure resistance, it is impossible to further reduce the wall thickness, which may not meet the demand of reducing weight.
As will be apparent from the above, in a laminated type evaporator, it is difficult to further reduce the thickness while achieving sufficient performance.
The present invention was made in view of the aforementioned circumstances, it is an object of the present invention to provide an evaporator capable of reducing the weight and the size while maintaining sufficient heat exchanging performance, the manufacturing method of the evaporator, a header member for the evaporator and a refrigeration system.
Another objects of the present invention will be apparent from the following explanation.